1. Field of the Invention
The present invention relates to an active control containment system for enclosure of biohazardous materials for use in medical, forensic and embalming procedures. The containment system is distinct from existing passive control measures consisting of personal protective equipment. The containment system can be used on biohazardous materials of human or animal origin which are living or dead at the time of examination.
2. Brief Description of the Prior Art
Autopsy tables used in hospitals typically have a downdrain system consisting of a discontinuous or perforated surface and an internal down-draft ventilation system for collecting blood and body fluids and drawing air-borne bacteria and aerosolized particles away from the operator. Even with the best of systems, however, some resistant, air-borne bacteria and aerosolized particles escape into the autopsy room, some of which will pass through an ordinary surgical mask. A hospital autopsy room also typically has a positive-pressure type ventilation system with air entering the room from the ceiling and leaving though vents in the walls, near floor level. With this form of ventilation, the air moves downwards past the operator at the table. This not only reduces smell but also helps to sweep away any infective vapors or particles. Sometimes the conditioned air is supplied from an overhead canopy. This arrangement increases the air flow past the operator but may cause undesirable turbulence around the operator's face which may increase (rather than decrease) the chance that the operator will inhale dangerous bacteria or aerosolized particles during performance of an autopsy.
Steps are also taken to protect the operator against being splashed with blood or other body fluids in compliance with the Centers for Disease Control (CDC) "Universal Precautions". Typical wear includes a lightweight shirt and trousers, such as those used by surgeons, an operating gown, waterproof apron, surgical cap and surgical or examining gloves. Non-slip, full length rubber boots are recommended together with protective goggles as acquisition of infection through the eye is possible because of the vulnerable nature of its membranes.
There are frequently spectators at an autopsy such as other doctors, medical students, law enforcement officers, prosecutors, etc. Because blood and other body fluids may be splashed on the floor and because of the aerosolized fluids and particles coming from the corpse, the spectators should be gowned, masked, booted and gloved also, all of which adds to the cost of conducting an autopsy. On the other hand, if they are improperly outfitted and are allowed unauthorized entry into the room wearing their everyday shoes, for example, they may carry blood and infected material out with them.
In general, the equipment used by morticians is not as sophisticated as that used in autopsies, increasing the likelihood that funeral workers will be exposed to biohazardous materials in the performance of their duties. For example, tables used by most morticians have no air exhaust system and there is often no plumbing assembly for collecting blood and body fluids or for disposing of embalming fluids. The majority of embalming fluids contain 10% formalin as formaldehyde, paraformaldehyde (a formaldehyde polymer), or trioxane (another formaldehyde polymer). Formaldehyde is associated with cancers of the lung, nasal and oral cavities. It is highly irritating to the upper respiratory tract and eyes and is a severe skin irritant and sensitizer. Deaths from accidental exposure to high concentrations of formaldehyde have been reported and there is an Occupational Safety and Health Administration (OSHA) standard limiting employee exposure.
To appreciate the extent of a mortician's exposure to formaldehyde, it is necessary to know something about the embalming process. When a body is embalmed, embalming fluid is injected under pressure into the arterial system, and blood is drained from the venous system, sometimes simultaneously and sometimes intermittently. The blood drains as it is carried through the vascular system by the pressure of the injected embalming fluid and by gravity. When done properly, injected fluid will also enter the lymphatic system and ultimately drain into the venous system, the goal being to have the embalming fluid permeate the tissues in order to preserve them. Since the injected embalming fluid follows the path of least resistance, some tissues may not be perfused, resulting in varying degrees of preservation. Techniques such as massage, manipulation of the body parts (lowering the arms, for example), and restriction of drainage are used to avoid such problems.
The number and location of injection sites in non-autopsied bodies depend on the funeral director's technique and the success of initial attempts at arterial injection. Sometimes the entire body can be embalmed through one arterial access site, but often more than one is required. The general approach is for the funeral director to select a primary injection site, perform arterial injection, assess the adequacy of perfusion, and then use secondary sites as needed to ensure perfusion of all body regions. In single-point injection, an artery and vein at one location are used for injection and drainage, respectively. Split injection utilizes an artery at one side and a vein at another side. In restricted cervical injection, both common carotid arteries are used and fluid is injected to the head through both arteries and to the remaining portions of the body through a tube directed downward in the right common carotid artery, with drainage being taken from the right jugular vein. Sectional injection uses a primary site and selected additional sites such as the brachial or radial artery in the arms. Six-point injection utilizes both common carotids, both axillary or brachial arteries in the arms, and both femoral or external iliac arteries in the groin.
After arterial embalming and depending on the mortician's practice, the cadaver is eviscerated through a midline incision and all the internal organs removed and discarded separately. The internal cavity is stuffed with absorbent material and sewed closed. Alternatively, the internal organs may be left in place and a trocar may be used to aspirate liquefied material from the viscera and body cavities. When aspiration is complete, a quart or more of concentrated embalming fluid may be injected through the trocar.
When an autopsy has been performed on the body, other procedures come into play, requiring additional handling of the body by the mortician. For example, when the brain has been removed and there is a freely removable skullcap, embalming of the face requires cannulation of the carotid artery at the side of the neck with clamping of the middle cerebral artery within the inner side of the skull. Embalming fluid will spill onto the table from the cut middle cerebral vein while the face is massaged. When the abdominal cavity is already emptied of internal organs, the abdominal wall and legs can be embalmed by cannulation of the common iliac arteries within the groin while the abdominal wall and legs are massaged. Embalming fluid will spill into the abdominal cavity, from which it is removed with a pump or ladle.
Unlike autopsy rooms, most embalming rooms used by morticians have no positive-pressure type ventilation system. A fan or a standard office air-conditioner merely recirculates the formaldehyde, air-borne bacteria and aerosolized particles within the closed room, possibly recirculating contaminants to adjacent rooms. Funeral home workers, particularly those handling human remains, are therefore at risk of infection and exposure to formaldehyde, OSHA standards (described below) frequently not being met. Some morticians also have the false perception that whatever organisms that caused mortality in the cadaver will become nonviable when their host is dead and fail to observe "Universal Precautions" (described below) regarding protective clothing, etc., further increasing the risk of infection.